The hitherto known strain gauges are of two types. The first one, makes use of metal foil (Micro-Measurements, Measurements Group, Vishay Intertechnology, Inc., P.O.Box 306, 38905 Chase Road, Romulus, Mich. 48174) pressed between two insulating laminates and the second one, uses the silicon material (Kulite Semiconductor International Ltd., One Willow Tree Road, Leonia, N.J. 07605) having diffused layer formed by impurity drive-in at high temperature in an inert gas. The gauges thus formed exhibit 2-5 as the gauge factor for the former type and 45-175 for the latter version. Such gauges are fragile and are temperature sensitive too. The substrate is commonly used to mount the gauge onto it.
There is a definite need for the enhancement of gauge factor for improving the signal conditioners and for developing the sensors for medical applications.
Our studies have shown that such strain gauge of high gauge factor is not available and is not possible with existing material technology. Our studies have also provided us the experimental fact that it is possible to increase the gauge factor by enhancing the conductive phase size of thick film resistive material. As per our process the surface morphology of the thick film resistor material gets converted to long conductive phases and their tunnel distance get enhanced. This in turn decreases the effective sheet resistance and enhances the gauge factor through geometrical and piezoresistive effects. To the best of our knowledge till date such gauges based on thick film technology having enhanced gauge factor are not available internationally.